Over a century had passed since Oboro first walked the earth as an immortal being.
The two maids who had once faithfully served him, Chiyoko and Rina, had long since passed into memory; their mortal lives had been claimed by time, while he remained unchanged. He wasn't even present to witness their final moments, a reality that weighed heavily on his conscience during quiet nights.
Since the twilight of the Edo period, Oboro had wandered the country alone, beginning his travels when he appeared to be in his thirties. By then, Chiyoko and Rina had grown too frail to accompany him on his journeys as they had in their youth. The roads he walked were lonely, marked only by his footsteps and the whisper of the wind through ancient trees.
His mission remained constant yet complex. With practiced precision, he used his transformation cards to alter the fundamental nature of demons while simultaneously seeking out exceptional and determined members of the Demon Slayer Corps. He bestowed experience cards upon these chosen few, accelerating their growth in ways that defied natural progression.
This combat experience strengthened the demons, making them more formidable adversaries, while pushing the swordsmen to master increasingly sophisticated breathing techniques. This delicate balance formed the foundation of his grand design.
For over four decades, Oboro had tracked the movements of Gyutaro and his sister, Daki. The siblings had carved a bloody path through the ranks of the Twelve Demon Moons; their hunger for vengeance drove them to hunt down Upper Ranks with relentless determination. While they had successfully eliminated numerous Lower Ranks, only one Upper Rank, Kaigaku, had fallen to their combined might.
Kaigaku's ascension to Upper Rank status occurred during the final years of the Edo period, predating Gyutaro's transformation. However, his unremarkable early performance kept him beneath Oboro's notice, a fatal oversight that ultimately cost Kaigaku his existence. His relative inexperience with the Demon Slayer Corps' evolving tactics, coupled with his limited exposure to the new generation of swordsmen, left him dangerously unprepared.
This weakness proved to be Gyutaro's opportunity and Kaigaku's doom.
The remaining four Upper Ranks presented an entirely different challenge. They had each endured countless battles and tribulations to reach their current positions, and their strength now surpassed that of their original incarnations from the timeline Oboro remembered. The complexity of the current situation had taught them caution, making them exceptionally skilled at concealment and misdirection.
Even the enhanced Demon Slayer Corps struggled against these evolved Upper Ranks. Doma and his companions had become masters of shadow and deception, striking only when victory was assured, then vanishing back into the darkness.
Muzan's awareness of Gyutaro's existence had become undeniable. Six months prior, the Demon King had orchestrated an elaborate trap, deploying Doma, Hantengu, and several Lower Ranks in a coordinated assault designed to capture the rogue siblings. Had it been a single Upper Rank facing the brother-sister duo, they might have found themselves devoured instead.
The world itself had transformed beyond recognition.
The Taisho era had dawned, bringing with it the fall of the shogunate system that had defined Japan for centuries. Yet, thanks to Oboro's influence, humans, not demons, claimed the reins of power. For those demons who sought to dominate humanity, their ultimate goals remained frustratingly distant.
The shift from a centralized shogunate to a more democratic system redistributed power among multiple officials, diluting any single individual's ability to influence. Oboro's former status as a shogunate retainer had become meaningless, eliminating his official channels for gathering intelligence and maneuvering politically. But these losses no longer concerned him.
The foundation he had spent decades building was now self-sustaining. With the Demon Slayer Corps serving as humanity's shield, any demon attempting to infiltrate or attack high-ranking government officials would face immediate and overwhelming resistance.
Humanity had achieved something unprecedented; they had learned to coexist with demons while maintaining their dominance. In this world, only two species mattered: humans and demons, and humanity unquestionably held the moral high ground.
Shanyang Road stretched through the mountainous terrain not far from Kyoto's ancient borders.
The acrid smell of gunpowder still lingered in the air where a brutal conflict had recently ended. Smoke drifted lazily from scattered fires, carrying with it the metallic scent of blood and death. The battlefield was littered with at least two hundred bodies, their uniforms bearing the modern styling that had become standard in this era.
Despite their exhaustion, the survivors moved with military precision, their clothing a fascinating blend of traditional and contemporary elements. Each soldier wore the standardized uniform of the government's demon-hunting division; however, traditional katana still hung at their sides, alongside newfangled firearms representing the march of technological progress.
This engagement typified the ongoing struggle between humanity and demonkind: an official demon-hunting army, trained by Demon Slayer Corps swordsmen and equipped with ancient wisdom and modern weapons. These soldiers possessed rudimentary breathing techniques, enough to enhance their physical capabilities, but they lacked the advanced methods that defined true Corps members.
The Ubuyashiki clan maintained strict control over the deeper mysteries of breathing techniques. Only those who joined the Demon Slayer Corps with pure intentions, those driven by genuine hatred of demons or the desire to protect innocent lives, were deemed worthy of such knowledge. However, these government soldiers were motivated by duty, patriotism, or simply survival. They carried too many conflicting desires to be trusted with the Corps' most sacred techniques.
The Ubuyashiki family had learned hard lessons about the corrupting influence of power. They refused to risk the world's fragile peace by allowing such abilities to fall into the wrong hands.
This careful balance represented generations of adaptation. While Ubuyashiki Kuno and Kagaya initially struggled to navigate Oboro's manipulations and forced cooperation with the government, their successors finally achieved a sustainable equilibrium. The Demon Slayer Corps remained independent while providing essential training and support to official forces, a partnership that would have been impossible under the rigid hierarchies of the Edo period, but which flourished in the more flexible Taisho democracy.
However, killing demons required more than basic breathing techniques and conventional weapons. The harsh reality was that Swordsmith Village, despite its exceptional skill, could never produce enough Nichirin swords to arm entire battalions. They were already stretched beyond capacity simply maintaining the blades of active Corps members.
The solution lay in a revolutionary innovation: the Demon Hand.
These specialized weapons resembled traditional swords, but they were forged through an entirely different process. While not as potent as true Nichirin blades, the Demon Hands possessed enough spiritual energy to destroy ordinary demons. The creation process was complex and deeply personal. Master swordsmen who had achieved significant mastery of breathing techniques would channel their internal energy into their blood during the forging process, imbuing the metal with their will and spiritual strength.
Two critical factors determined a Demon Hand's effectiveness. First, time: unlike the eternal power of Nichirin swords, these weapons were temporary. The spiritual energy gradually dissipated as the blood dried and lost its connection to the living wielder. The second factor was the creator's willpower. Just as Oboro had learned to suppress Muzan's cursed cells through sheer determination, crafting a Demon Hand required absolute faith and mental fortitude. Without these qualities, the forging process would fail entirely.
The existence of Demon Hands itself testified to the evolution of the Demon Slayer Corps. Their willpower had grown stronger and more focused with each passing generation, refined by constant conflict and necessity.
The Corps had been forced to evolve or face extinction at the hands of the inheritors and Muzan's forces. This was precisely the outcome Oboro had envisioned from the beginning.
Reports regularly reached him of Hashira achieving the legendary "transparent world" through advanced breathing mastery. The Demon Slayer Marks, the Crimson Blades, and the Transparent World were all phenomena that had appeared decades ahead of their original timeline. Resources like the Demon Hand, which had never existed in the world he remembered, now played crucial roles in humanity's survival.
Yet, despite all this progress, Oboro knew it wasn't enough. His ambitions demanded even greater innovation and evolution.
"Sir!"
The soldiers worked methodically to clear the battlefield, their movements practiced and efficient despite the surrounding carnage. Suddenly, one of the swordsmen spotted a lone figure approaching through the darkness. The figure moved with unhurried steps along the mountain path.
The soldier's training kicked in immediately. He spun toward his commanding officer, his voice sharp with alarm.
Every blade sang as it cleared its sheath. The men formed a defensive perimeter with the fluid precision of veterans who had faced the supernatural too many times to take chances.
Their pre-battle briefings had been explicit: no civilians should be anywhere near this conflict zone. Any unidentified figure could be a demon, and distinguishing friend from foe in the darkness was nearly impossible.
This particular engagement targeted the inheritors' forces rather than Muzan's traditional demon hierarchy. Unlike Muzan's subordinates, who typically operated as solitary hunters, the Inheritors had learned to coordinate their efforts and fight as organized units.
"An elder?" The commanding officer squinted through the gloom, his weathered features creasing with confusion.
The approaching figure resolved into an elderly man whose appearance defied easy categorization. His hair had turned completely white, and though his frame appeared thin and fragile, his face retained an almost youthful quality. Though wrinkles marked his features, there were surprisingly few for someone of his apparent age.
Most striking were his eyes, which blazed with an inner fire that spoke of experiences spanning decades, perhaps even centuries. They held none of the dimness or confusion of advanced age; instead, they radiated an intensity that made hardened soldiers instinctively step back.
"Those clothes," the officer whispered as recognition dawned.
The stranger wore a black haori over a traditional samurai outfit from a bygone era. Wooden geta adorned his feet, not the lightweight, modern versions worn for festivals or casual outings, but the heavy, traditional style that had largely disappeared from daily use. Such footwear was now seen only in the most remote villages or among those who clung desperately to the old ways.
"A black haori? Could you be the God of Swordsmen?" The officer's voice cracked with disbelief and growing excitement.
His words rippled through the assembled soldiers like a physical force. Their weapons lowered slightly as wonder replaced wariness in their expressions.
The God of Swordsmen existed at the intersection of legend and reality, a figure whispered about in barracks and training grounds across the nation. Stories claimed that exceptional warriors would occasionally encounter this mysterious being, who would grant them incredible power and insight.
No one knew his true identity or origins. There were heated debates about whether he was human, a spirit, or something else entirely. What remained consistent across all accounts was the transformation he brought to those he deemed worthy.
Even in the modern age of steam and steel, countless samurai maintained shrines dedicated to the God of Swordsmen and offered prayers for the chance to receive his blessing. His legend grew stronger as more warriors emerged, claiming to have been touched by his power. Many of these warriors went on to become renowned demon slayers and protectors of humanity.
Oboro approached the trembling officer with measured steps, each footfall silent on the blood-soaked earth. The man's face flushed crimson with excitement and awe as he dropped to his knees in perfect dogeza.
The surrounding soldiers held their breath, afraid that even the slightest sound might disrupt the sacred moment unfolding before them.
"Accept your sacred mission of demon slaying and grow stronger in service to humanity," Oboro said with quiet authority. His voice carried the weight of centuries.
A card materialized between his fingers, invisible to all but him, before dissolving into streams of pure light that flowed directly into the kneeling officer.
The experience card's activation hit the officer like a thunderbolt to the brain. Decades of combat knowledge, strategic wisdom, and refined breathing techniques flooded the officer's consciousness in an overwhelming torrent. Memories that weren't his own, battles against demons, both ancient and contemporary; the subtle variations of sword forms, perfected through countless encounters; and the deeper mysteries of spiritual energy manipulation, all crashed into his mind simultaneously.
When awareness finally returned, the mysterious figure had vanished as silently as he had appeared, leaving only the lingering sense that something profound had occurred.
The other soldiers gathered around their commander. Their faces showed a mixture of envy and genuine excitement for their leader's good fortune. They had witnessed something that would become another legend, another story to be told in hushed voices around campfires.
"Divine power. It was truly divine power," the officer whispered, his voice trembling with disbelief and newfound understanding.
Every cell in his body hummed with enhanced vitality. His breathing felt deeper and more controlled, as if he had suddenly gained access to techniques that had previously been beyond his comprehension. The sword at his side seemed lighter and more responsive, as if it had become an extension of his will rather than merely a tool.
The transformation was complete, and with it, another piece of Oboro's grand design fell into place.